1. Field of the Invention
The present invention relates generally to sports equipment. The present invention relates more particularly to equipment for the sport of snowboarding, and to safety devices used to prevent injury while snowboarding.
2. Background
Snowboarding is a winter sport that has gained in global popularity and is now commonly practiced at most ski resorts in the United States. Many Americans have already purchased equipment for snowboarding. This equipment usually includes a snowboard, snowboarding boots, and bindings to attach the snowboarding boots to the snowboard.
Two general types of snowboard bindings are owned by Americans today: xe2x80x9cstrap-inxe2x80x9d snowboard bindings and xe2x80x9cclick-inxe2x80x9d snowboard bindings. Both types of bindings are attached to the snowboard by threaded fasteners and are not removed from the snowboard during use. Neither type of binding is designed to separate from the snowboard under the force of a crash.
With strap-in bindings, the snowboarding boot is attached to the bindings by straps that must be connected and tightened. The straps must be loosened and/or disconnected to detach the snowboarding boots from the bindings. Strap-in bindings also serve to structurally reinforce the snowboarder""s ankles while snowboarding (i.e. when the straps are tightened). Because the strap-in bindings provide the necessary rigidity around the snowboarder""s ankles, the snowboarding boots need not be designed to be rigid or stiff. Therefore, the snowboarding boots that are designed to be compatible with strap-in bindings can be designed to be comfortable for normal walking. However, the feature facilitating comfortable boot design does not significantly enhance safety while snowboarding nor significantly reduce the chance of injury while snowboarding. Contemporary strap-in bindings are not designed to allow the separation of the boots from the snowboard under the force of a crash.
Click-in bindings better facilitate the intentional attachment and detachment of the snowboarding boots to and from the bindings. With click-in bindings, the snowboarding boots are specially designed or adapted to attach to the bindings, and detach from the bindings, upon a specific intentional action accomplished by the snowboarder. A snowboarder typically needs to detach one foot from the snowboard at the bottom of the ski slope to enable the snowboarder to push that foot against the snow for self-propulsion to the ski lift. The snowboarder must then reattach the disconnected foot to the snowboard after arriving at the top of the ski slope. Therefore, the ease of intentional detachment and reattachment can be an important performance characteristic of snowboard bindings. However, snowboarding boots that are specially designed to function with click-in bindings are typically very stiff because the boot must provide the ankle reinforcement necessary for snowboarding, without the additional structural support provided by strap-in bindings. Consequently such boots are less comfortable for walking than boots designed for use with strap-in bindings. Moreover, the feature facilitating intentional disconnection of the boots from the bindings does not significantly enhance safety nor significantly reduce the chance of injury. Contemporary click-in bindings are not designed to allow the separation of the boots from the snowboard under the force of a crash.
In contrast with snowboarding equipment, skiing equipment has evolved to include sophisticated safety release mechanisms in the bindings that attach ski boots to skis. These safety release mechanisms have prevented many ski-related injuries. However, such safety release mechanisms are absent in commercially available snowboarding equipment.
One reason why commercially available snowboard bindings have not yet evolved to include safety release mechanisms is the presence of at least one additional important design requirement: the need for simultaneous release of both bindings (one for each of the snowboarder""s two feet) under the force of a crash. The release mechanisms that are typical of contemporary ski equipment do not satisfy that important design requirement. Therefore, there is a need for a practical safety release mechanism for snowboard bindings that can ensure simultaneous release of the bindings for both feet under the force of a crash. Furthermore, because of widespread fear among the purchasers of snowboarding equipment of the risk of injury associated with the release of only one snowboard binding and not the other, there is a commercial need for the safety release mechanism to provide clearly apparent and visually verifiable certainty in the simultaneity of the release.
Attempts have been made in the prior art to design a practical safety release mechanism for snowboard bindings. These designs seem to have been inspired by the safety release mechanisms developed for ski bindings, since their focus remains on the separation of each individual boot from all or part of its binding. The attempts have not contemplated a safety release that could separate standard snowboard bindings, including contemporary strap-in bindings, from the snowboard in response to the forces of a crash. Furthermore, prior art bindings for individual boots that release when that boot is twisted or lifted may not release when the snowboarder""s entire trunk is twisted by the snowboard. When the torque applied by the snowboard to the snowboarder is about an axis normal to the snowboard, but is a torque about the longitudinal axis of the snowboarder""s entire body rather than the twisting of an individual foot, prior art bindings for individual boots may perceive this torque as a lateral shear force in the plane of the snowboard and consequently may not release. Many snowboarders suffer injuries to their lower spine as a result of such torques. Thus, there is a need for a safety release mechanism that will release when a torque about an axis normal to the snowboard, but about the snowboarder""s entire trunk rather than the twisting of an individual foot, exceeds a given threshold. Many prior art designs have been variants of click-in bindings that usually require the snowboarder to wear a specially designed or adapted boot. Many Americans have already purchased snowboard boots that they chose because of comfort, warmth, or style. Accordingly there is a need for a new safety release mechanism that will reduce the forces and torques applied to the snowboarder""s legs and trunk during a crash, but will not render already-purchased snowboarding boots and bindings obsolete.
The disclosed invention provides a novel and effective safety device for snowboards. A preferred embodiment of the disclosed invention provides a safety release mechanism that has the advantage of being able to function with standard, already-purchased, contemporary snowboarding boots and bindings. Another advantage of the disclosed invention is that it provides a safety release mechanism that is responsive to crash forces and torques occurring in directions that are most likely to result in injury while snowboarding. For example, the disclosed invention has the advantage that it will release when a crash torque about an axis normal to the snowboard exceeds a given threshold, even where that torque is about trunk of the snowboarder""s entire body rather than the twisting of an individual foot. A further advantage of the disclosed invention is that it provides a safety release mechanism having a force threshold for release that can be adjusted according to the magnitude of crash forces and torques that are expected for a particular snowboarder. For example, the force threshold for release can be adjusted according to the weight and ability level of the snowboarder. A further advantage of the disclosed invention is that it provides clearly apparent and visually verifiable certainty to a potential purchaser that, in the event of a crash, both bindings must always either release simultaneously or else not release at all. A further advantage of the present invention is that it provides a safety release mechanism that reduces the leverage that external objects can apply to the snowboarder""s legs and trunk during and after a crash. A preferred embodiment of the present invention has the added advantage of continuing to prevent excessive spreading or crossing of the snowboarder""s legs even after a safety release has occurred. Additional advantages and features of the invention will become apparent from the description that follows, and may be realized by means of the instrumentalities and combinations particularly pointed out in the appended claims.
According to one aspect of the invention, bindings that would normally be fastened to the snowboard are instead both fastened to a binding support platform. A platform retention assembly is fastened to the snowboard. The platform retention assembly includes preloaded compliant members that form interfaces with contours on the binding support platform. The interfaces prevent the binding support platform from separating from the platform retention assembly except when a force or torque applied to the snowboard exceeds a set threshold (i.e. except under crash conditions). The platform retention assembly includes firm members, surfaces, or edges that contact firm mating members, surfaces, or edges on the binding support platform to prevent pure translation of the binding support platform relative to the platform retention assembly in the plane of the snowboard. The firm members, surfaces, or edges, and the firm mating members, surfaces, or edges are arranged such that the contacts between them, when projected onto the plane of the snowboard, are all tangent about one mutual center point.
According to another aspect of the invention, a platform retention plate is fastened to the snowboard. The binding support platform is part of a binding support platform assembly that includes preloaded compliant members that form interfaces with contours on the platform retention plate. The interfaces prevent the binding support platform assembly from separating from the platform retention plate except when a force or torque applied to the snowboard exceeds a set threshold (i.e. except under crash conditions). The platform retention plate includes firm members, surfaces, or edges that contact firm mating members, surfaces, or edges on the binding support platform assembly to prevent pure translation of the binding support platform assembly relative to the platform retention plate in the plane of the snowboard. The firm members, surfaces, or edges, and the firm mating members, surfaces, or edges are arranged such that the contacts between them, when projected onto the plane of the snowboard, are all tangent about one mutual center point.
Different practical applications of the invention can enhance various metrics of performance. For example, according to one practical application of the invention, the preload force of three or more of the preloaded compliant members that facilitate retention of the binding support platform can be adjusted simultaneously by setting the position of a single centralized component. According to another practical application of the invention, snow and debris are excluded from the retention mechanism and interfaces by a cover. Yet; according to another practical application of the invention, longitudinal flexibility is enhanced by leaving the retention mechanism uncovered and thereby arriving at a lower profile design. According to another practical application of the invention, longitudinal flexibility is enhanced by separating the platform retention plate into two plates, or separating the plate underlying the platform retention assembly into two pieces (each fastened to the snowboard). According to another practical application of the invention, cost is reduced by limiting the number of preloaded compliant members to three. Yet, according to another practical application of the invention, four interfaces are located near the corners of the binding support platform to enhance the transfer of controlling torques from the snowboarder to the snowboard.